1. Field of the Invention
The present invention relates to a developer amount regulating member used for developing an electrostatic latent image formed on an image holding member to visualize the latent image. Particularly, the present invention relates to a developer amount regulating member for regulating the amount of the developer coated on the surface of a developer holding member for holding and carrying the developer to a development region to apply a charge to the developer by triboelectric charging, and a development device using the developer amount regulating member.
2. Description of the Related Art
As shown in FIG. 1, a conventional known development device comprises a developer holding member 3 (referred to as a "development sleeve" hereinafter) mounted in a development container 2 with a small space from an electrophotographic photosensitive member 1, a developer amount regulating member 4 (referred to as a "development blade" hereinafter), an elastic roller 5, and a one-component developer 6 (referred to as "toner" hereinafter). As means for regulating, to a thin layer, the thickness of a toner layer held and carried to the development unit by the development sleeve, a method is employed in which the developer amount regulating member is brought into contact with the development sleeve, and the toner is passed through the contact portion between the developer amount regulating member and the development sleeve to regulate the thickness of the toner layer, to form a thin toner layer on the development sleeve and apply a triboelectric charge for developing a latent image to the toner in the contact portion.
Examples of such a developer amount regulating member include a rubber plate, a metallic thin plate, a resin thin plate, and a lamination thereof. Particularly, for new types of toner such as low-melting-point toner (sharp melting toner) for fixing at a temperature lower than conventional temperatures from the viewpoint of energy saving, a nonmagnetic toner for forming color images, and polymerization toner, Japanese Patent Laid-Open No. 9-50185 discloses a development blade made of a polyamide elastomer which has the property of applying an appropriate triboelectric charge to a developer, and elastic properties. Therefore, the use of such a development blade causes uniform contact force between the developer holding member and the development blade and enables the developer to be held on the developer holding member with a uniform thickness and a uniform amount of triboelectric charge, thereby preventing charge-up of the developer and realizing a high image density. However, in order to effectively triboelectrically charge the toner, it is necessary that the blade surface be a mirror surface, and specularity be held by injection molding using a mold finished to a mirror surface.
However, when a polyamide elastomer is molded by injection molding to realize a blade surface having good surface accuracy by transferring the mirror surface of a mold, chargeability of the toner deteriorates in long-term storage in an environment of normal temperature and normal humidity, and a fogging phenomenon occurs in which the toner is developed in a non-image region.
This phenomenon becomes significant in long-term storage in an environment of high temperature and high humidity.
As a result of examination of the cause of this phenomenon, the cause was confirmed to be that a polyamide elastomer contains 3000 to 5000 ppm of polyamide dimer, and the polyamide dimer bleeds to the blade surface to bloom the blade surface and roughen the surface.